Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Deep-sea jelly uses glowing red lures to catch fish

08.07.2005


This newly discovered deep-sea siphonophore is about 45 cm (18 inches) long. The upper half of the colony consists of swimming bells that pulse like jellyfish to keep the colony moving through the water. The lower half carries hundreds of pale white stinging tentacles, which are used to capture small deep-sea fishes.
Image: (c) 2003 MBARI


This photograph shows the newly discovered siphonophore’s tentilla—tiny filaments that branch off the main tentacles. Each tentilla contains thousands of stinging cells. The red lures are on separate stalks, which move up and down, causing the lures to wiggle like swimming copepods (a typical food of small midwater fishes).
Image: Steven Haddock (c) 2004 MBARI


As successful fishermen know, if you want to catch fish, you have to use the right bait or lure. This is true even in the deep sea, where scientists recently discovered a new species of jelly that attracts fish by wiggling hundreds of glowing red lures. This is the first time any marine invertebrate has been found to use a bioluminescent lure or to display red bioluminescence. This discovery is described in an article written by Steven Haddock of the Monterey Bay Aquarium Research Institute (MBARI), along with several coauthors, in the July 8, 2005 issue of Science magazine.

It has been estimated that about 90 percent of deep-sea animals are bioluminescent. Yet in many cases, scientists do not know how these animals benefit from the energy-intensive process of producing their own light. Some jellies use bioluminescence as a defense—they glow when disturbed in order to light up their predators, making their attackers vulnerable to even larger animals. A few deep-sea fishes and squids have glowing organs that look like lures, but even these animals have never been observed actually using their glowing organs to capture prey.

MBARI marine biologist Steven Haddock has studied glowing marine animals for over a decade, focusing on gelatinous animals such the siphonophores described in his recent article. Related to the typical round "jellyfish" that sometimes wash up on beaches, siphonophores are colonial animals, arranged in chains that in some species can be dozens of meters long. The members of a colony specialize at different tasks. Some form swimming bells, which pulse slowly, pulling the colony through the water like a long, fluid freight train. Others specialize in feeding, and sport stinging tentacles.



Almost all siphonophores are bioluminescent, but scientists know little about why and how they glow. Siphonophore colonies are notoriously difficult to study—they often break into pieces when disturbed or captured. For this reason, Haddock spent hundreds of hours using MBARI’s remotely operated vehicles (ROVs) to observe siphonophores in their native habitat, thousands of meters below the sea surface.

The siphonophore featured in Haddock’s article (which is an unnamed species in the genus Erenna) lives at depths of 1,600 to 2,300 meters, where fish are few and far between. For this reason, Haddock was surprised to observe small fish in their guts. He found himself wondering how these jellies could capture enough fish to survive in their sparsely inhabited environment. Examining the siphonophores under the microscope, he discovered that interspersed among their stinging tentacles were thin rod-like structures. These "tentilla" were tipped with red, glowing blobs.

Several lines of evidence eventually led Haddock and his coauthors to the conclusion that these red blobs served as lures for small deep sea fish. Their first clue lay in the siphonophore’s behavior. Jellies that use bioluminescence for self defense tend to have lights distributed all around their body, which flash brightly when disturbed (the "burglar alarm effect"). In contrast, the Erenna siphonophores kept their bioluminescence very localized and under tight control, suggesting that their lights had an entirely different function.

Continuing his microscope work, Haddock found more specific clues—the red, glowing blobs were shaped remarkably like the bodies of deep-sea copepods, a major food item for small deep-sea fish. Furthermore, the tentilla flicked back and forth repeatedly so that the glowing lures darted through the water just like swimming copepods. Finally, at least one siphonophore’s digestive system contained both fish and lures, suggesting that the lures were ingested along with the fish.

Haddock sees these glowing lures as Erenna’s way of adapting to a difficult environment. As he put it, "Most siphonophores set a big web of tentacles to catch animals that happen to swim by. But this jelly doesn’t deploy its tentacles very far. In an environment where fish are rare, it uses deception to attract fish instead of casting a wide net to capture them."

After discovering lures on this new species of siphonophore, Haddock and his coauthors looked at several related species and noticed similar glowing structures. He believes that these structures also serve as lures, but were overlooked or misinterpreted by previous researchers. He explains, "This discovery was a big paradigm shift for us—most jellies were thought to use bioluminescence for defense, but once we saw this, it made us realize that the same thing was happening in other species."

Erenna’s glowing red lures may also force scientists to take a new look at the role of red light in the deep sea. Red bioluminescence is extremely rare, and the prevailing view among marine biologists has been that most deep-sea animals cannot detect red light at all. However, because deep-sea fishes are so hard to bring to the surface intact, we know very little about their physiology. Haddock’s work suggests that some deep-sea fishes may not only see red light, but routinely use it in finding food.

Kim Fulton-Bennett | EurekAlert!
Further information:
http://www.mbari.org

More articles from Life Sciences:

nachricht Fine organic particles in the atmosphere are more often solid glass beads than liquid oil droplets
21.04.2017 | Max-Planck-Institut für Chemie

nachricht Study overturns seminal research about the developing nervous system
21.04.2017 | University of California - Los Angeles Health Sciences

All articles from Life Sciences >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: Deep inside Galaxy M87

The nearby, giant radio galaxy M87 hosts a supermassive black hole (BH) and is well-known for its bright jet dominating the spectrum over ten orders of magnitude in frequency. Due to its proximity, jet prominence, and the large black hole mass, M87 is the best laboratory for investigating the formation, acceleration, and collimation of relativistic jets. A research team led by Silke Britzen from the Max Planck Institute for Radio Astronomy in Bonn, Germany, has found strong indication for turbulent processes connecting the accretion disk and the jet of that galaxy providing insights into the longstanding problem of the origin of astrophysical jets.

Supermassive black holes form some of the most enigmatic phenomena in astrophysics. Their enormous energy output is supposed to be generated by the...

Im Focus: A Quantum Low Pass for Photons

Physicists in Garching observe novel quantum effect that limits the number of emitted photons.

The probability to find a certain number of photons inside a laser pulse usually corresponds to a classical distribution of independent events, the so-called...

Im Focus: Microprocessors based on a layer of just three atoms

Microprocessors based on atomically thin materials hold the promise of the evolution of traditional processors as well as new applications in the field of flexible electronics. Now, a TU Wien research team led by Thomas Müller has made a breakthrough in this field as part of an ongoing research project.

Two-dimensional materials, or 2D materials for short, are extremely versatile, although – or often more precisely because – they are made up of just one or a...

Im Focus: Quantum-physical Model System

Computer-assisted methods aid Heidelberg physicists in reproducing experiment with ultracold atoms

Two researchers at Heidelberg University have developed a model system that enables a better understanding of the processes in a quantum-physical experiment...

Im Focus: Glacier bacteria’s contribution to carbon cycling

Glaciers might seem rather inhospitable environments. However, they are home to a diverse and vibrant microbial community. It’s becoming increasingly clear that they play a bigger role in the carbon cycle than previously thought.

A new study, now published in the journal Nature Geoscience, shows how microbial communities in melting glaciers contribute to the Earth’s carbon cycle, a...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

Expert meeting “Health Business Connect” will connect international medical technology companies

20.04.2017 | Event News

Wenn der Computer das Gehirn austrickst

18.04.2017 | Event News

7th International Conference on Crystalline Silicon Photovoltaics in Freiburg on April 3-5, 2017

03.04.2017 | Event News

 
Latest News

New quantum liquid crystals may play role in future of computers

21.04.2017 | Physics and Astronomy

A promising target for kidney fibrosis

21.04.2017 | Health and Medicine

Light rays from a supernova bent by the curvature of space-time around a galaxy

21.04.2017 | Physics and Astronomy

VideoLinks
B2B-VideoLinks
More VideoLinks >>>